I'm trying find some best practices for incorporating a rocket mass heater in a greenhouse. Greenhouses are extremely leaky structures (much higher rates of air infiltration than any home). I can imagine the heater would create additional cold air infiltration -- sucking heat into the heater and pumping it outside. Cold air will naturally be drawn into the structure.
I've seen a post commenting that their air intake came from the outside. That's a huge compromise in efficiency as well, but perhaps not as great. It seems rocket mass heaters have such a high temperature, they can still heat very cold intake air to the same level as pre-warmed (indoor) air, without much difference in performance? That is just my guess.
Greenhouses are also very humid environments. I don't know if that extra humidity could be an issue in the exhaust pipe. Is water vapor in the exhaust pipe generally a problem in the first place?
Any other general recommendations for tailoring this system to a greenhouse application would be helpful. Thanks in advance.
Lindsey; I'm entering my third season with a RMH in our greenhouse / studio. In short, it's everything I ever wanted out of a wood burner ! Last season in northern montana, I used just over 4 cord of wood!!! to keep our greenhouse 65+ everyday and 38+ or better every night with no fire from 10 at night till 7 or so next morning ! My old wood gobbler used 12-15 cords to do the same thing, only it was too hot or too cold most of the time and my wife would feed the stove till midnight and i would continue from 4 am on, not fun ! My RMH is an 8" J tube , all brick , barrel heavily cobbed, 14' long mass of cob & slate lasagna encased with a red brick surround ,with an indoor vertical chimney rising 14' to the peak. All parts of the room are comfy warm all the time ! no more hot & cold spots! Depending on the outside temps at the time , we do keep it going all day. Not as hard as some folks seem to think, once you have it going good every 40 minutes or so (wife uses a timer) we go out and refill the feed tube. A hot 8" core will easily burn a 6" red fir round with smaller sticks around it, this will last close to an hour but you will not get an optimum burn as it dies down. If your fire does go out... there is nothing easier than relighting a warm rmh ! Hardest part is relighting the lighter six times because the draft keeps sucking it out before you can get your paper relit. I now crumple up a piece in my hand , light it and then stuff it in the top of the feed tube... works perfect! When you let your feed tube burn out for the night, simply cover with extra brick to slow the draft and your mass will stay toasty warm all night . My greenhouse is 12x20 wood framed with a high peaked roof. We utilize a (mud room/entry way )to minimize exposure to the outside temps. Covered with solex and glass, with a dirt floor. We grow succulents rather than vegetables so we don't water much during the winter, so humidity isn't an issue. RMH's in greenhouses has its own post here at permies that will have lots of ideas for you, check it out.